CLIMATE - A REVISION OF WINTER AND INTO SEPTEMBER WE GO.

Starting to see the heat engine wake up, the moisture content across the nation is also starting to increase and become activated along the areas of low pressure that is starting to emerge through the nation this week and into the weeks ahead.


Signals of early Spring are underway too, with the natural signals pointing to early Spring also observed, nature certainly giving those out loud and clear.


With the climate drivers in place, the forecast is shifting in line with where they are at. The Indian Ocean in a negative phase and the SAM starting to tend negative coupling that with this weird and protracted La Nina phase ongoing though the waters are warming a little but the peak of that warmth likely being observed now!


Let's take a look at the latest information together.


FORECAST VIDEO - CLIMATE OUTLOOK NEXT 6 WEEKS - TUESDAY 26TH JULY 2022

RAINFALL - MAIN POINTS

  • The wetter as we go idea is one that looks to verify for many areas for the remainder of Winter.

  • Flood risks are increasing for the southeast inland where the snowpack may be rained on more frequently with the higher moisture levels and warmer airmass ahead of frontal weather

  • Many areas leaning wetter than normal with the highest chance through the SWLD of WA, throughout the southeast inland and the interior running along the jet stream.

  • Northern areas may begin to see early season humidity and showers and thunderstorms developing in the coming weeks.


SOUTHEAST INLAND/FOOD BOWL

%Chance of exceeding or not exceeding the median rainfall for the coming 6 weeks

A wet signal continues through the nation's southeast with that to start unfolding from August with a wet start to the month. The rainfall signals continue to strengthen throughout August and into early September as the frontal barrage continues, the moisture deepens from the northwest via the subtropical jet stream pulling in the influence of the Indian Ocean. The heaviest of the rainfall is forecast to be along the ranges in VIC and west of the divide through NSW with that in keeping with the Indian Ocean Dipole. The east coast looking to be spared the heaviest of the rainfall, BUT this is dependent on whether we see an east coast low or not amongst the high levels of moisture and colder air clashing with the warmer air throughout the nation.

EASTERN INLAND

The rainfall signals are leaning above average for the period with the chance of above average rainfall developing from as early as next week with widespread cloud forming in response to the moisture increasing from the northeast, north and northwest and troughs passing through the southeast inland. This may be repeated time and time again throughout the coming weeks. As the nation continues to warm, and the moisture and influence from the Indian Ocean continues to increase, then we will likely see more inland rainfall spreading throughout the country and impacting large sections of QLD.

SOUTH AUSTRALIA

The signal for wetter as we go through Winter looks to unfold from August as expected with the moisture streaming in along the jet stream and interacting with a more robust period of frontal weather in the coming 2-3 weeks, leading to above average rainfall chances, especially in those areas exposed to the westerly wind regime. The wetter signal over the interior is expected to increase as well as we see moisture pulled into the subtropical jet stream and this is where we will see the presence of cloud bands increasing and this lifting the rainfall chances along cold fronts as they move through from west to east.

SOUTHWESTERN AUSTRALIA

The rainfall is expected to increase dramatically in the coming weeks as we see a more robust period of frontal weather passing throughout the nation's south. With the above average rainfall signals continuing through the interior, this denotes the presence of the jet stream and the Indian Ocean Dipole influence. That may largely stay north of Ag Areas through the SWLD. However, with the elevated SSTs sitting offshore the west and south coastal areas, this will lead to heavier rainfall along frontal weather and with the onshore northwest to southwesterly push. This will likely be the peak of the Winter westerly influence for 2022.

NORTHWEST AUSTRALIA

Humidity values are starting to come up over the northern parts of the nation with the increase in low level humidity being suppressed in terms of producing showers while ridging is in place. But as we see the ridging break down through the second half of August and the flow pattern tend a little more northeasterly, morning showers and isolated afternoon showers and thunderstorms may begin to return to forecast charts and packages from later in August and into September. Ahead of that, there is a moderate chance of large cloud bands sweeping through bringing the chance of patchy light rainfall.

NORTHEAST AUSTRALIA

The humidity values also increasing over the northeastern areas of the nation with the easterly winds carrying the higher moisture load via the elevated SSTs over the Coral Sea. The northeasterly flow, tending more unstable leading to higher chance of showers for this time of year, but rainfall coverage and intensity is dependent on the presence of low pressure through the state. At this time, the bulk of the most unstable air is forecast to be found further south of here but watch closely for the presence of westerly moving waves and upper troughs moving through the interior, interacting with the moisture. That is why I have kept most of the state under green which is leaning bias to wetter than normal conditions.

TEMPERATURES - MAIN POINTS


  • The overall trend is for warmer weather developing over the northwest and northern parts of the nation as the heat engine wakes up.

  • Elevated SSTs surrounding Australia will assist in the rapid warming for northern Australia and that has been observed in the past week.

  • Warm air will be transported southwards into the southern half of the nation with that clashing with colder air surging northwards into the nation.

  • With the warmer and more humid air involved in the mix, more widespread rainfall is forecast and the warmer the air gets, the more rainfall can be expected.

  • Severe weather season may kick off earlier than normal with the heat indices dictating that. So, watching the heat values over the coming weeks closely ahead of each system over Southern Australia.

NORTHWEST AUSTRALIA/HEAT ENGINE

%Chance of exceeding or not exceeding the median temperatures for the coming 6 weeks. The heat engine is forecast to wake up over the coming weeks, we have already seen that in recent days and the impact of that heat has started to increase the instability values over the nation ahead of weak cold fronts in the past 2 days. So that is enough of a signal to suggest that the IOD influence is forecast to be ongoing and that will lead to not only the wetter signals developing over the country, but also above average temperatures for much of the nation's interior.

EASTERN INLAND

Some of the heat values are being transported south and east through the nation via the upper-level northwest winds and surface westerly winds leading to a warmer few weeks on the way. Depending on cloud cover, the temperatures may be cooler/warmer than what is shown here overall, and this will be a feature to watch as it may dictate what is forecast for the months ahead.

SOUTHEAST INLAND/FOOD BOWL

Warmer few weeks on the way for the northern part of the bowl as this region sits just a little further north of the coldest air now and given that the flow pattern is more westerly in nature than southwesterly, this will transport the warmer air through to northern NSW and throughout much of southern QLD west of the divide. The warmer air being drawn south may spice up the frontal weather coming out of the west, clashing with the colder air surging behind frontal weather, may bring an early start to severe weather season for southeastern areas of the country. Land gales also could be a feature with the temperature gradient tightening up the pressure gradient.

SOUTHERN AUSTRALIA

The warmer bias at times, will work into the APY Lands and Northwest Pastoral District and back through to the southern NT. The further south the heat can come towards coastal areas on the Bight, the more volatile the weather is likely to appear along frontal weather sweeping through southern parts of SA. This may also support higher rainfall totals developing as we move throughout the coming weeks as well. The fluctuation in temperature supports a seasonal outlook for most Ag Areas in SA.

SOUTHWEST WA.

The colder bias continues for the west as this region sits under persistent westerly winds and cold fronts passing through at a higher frequency, this is leading to widespread cloud cover and rainfall above the norm. So, while the heat engine is starting to wake up, the heat will be deflected off to the east through SA and the NT into the eastern inland in the prevailing upper-level northwest winds.

KEY POINTS

Refer to the video for further information related to these points.

Make sure you check back on the daily weather videos both morning and night for further verification on this outlook forecast. These trend-based forecasts only sing when you marry it with the short- and medium-term forecast information.